NAIROBI, June 17 (Reuters) - Somali-linked Islamist militants killed at least eight people in a second night of attacks on Kenya's coast, after a raid on the town of Mpeketoni left at least 50 dead, the Kenya Red Cross and the Somali rebel group said on Tuesday.

Red Cross coordinator for the coast Mwanaisha Hamisi told Reuters that gunmen on Monday night attacked Poromoko area near Mpeketoni, which lies on the coast between Mombasa and the Somali border in the north, killing at least eight people.

"We raided villages around Mpeketoni again last night," Sheikh Abdiasis Abu Musab, the spokesman for al Shabaab's military operations, also told Reuters, saying it killed as many as 20 people, mostly police. "Our operations in Kenya will continue."

(Reporting by Abdi Sheikh in Mogadishu and Joseph Akwiri in Mombasa; Writing by Edmund Blair; Editing by Duncan Miriri)